Along with development of a network technology, massive services such as voices, data and videos may be transmitted by virtue of a network, thus a requirement on a bandwidth of the network increases, and a Passive Optical Network (PON) emerges to meet such a requirement. FIG. 1 is a topological structure diagram of a PON system according to a related PON technology. As shown in FIG. 1, the PON system is usually formed by an OLT at a network side, ONUs at a user side and an Optical Distribution Network (ODN), and usually adopts a point-to-multipoint network structure. The ODN is formed by single-mode optical fibers and passive optical devices such as an optical splitter and an optical connector, and provides an optical transmission medium for physical connections between the OLT and the ONUs. In order to further improve a bandwidth of a network, a PON system in which multiple paths of wavelengths are transmitted in a trunk optical fiber and each path of wavelength is accessed by virtue of a time division technology is provided, and this type of PON system is called as a Time Wavelength Division Multiplexing (TWDM) PON system.
FIG. 2 is a topological structure diagram of a TWDM PON system according to a related PON technology. As shown in FIG. 2, there are multiple TWDM Channel Terminations (CTs) in a TWDM PON OLT, and each TWDM CT processes a pair of uplink and downlink wavelength CHs (forming a TWDM CH) which are associated with each other, and provides access and maintenance service for all ONUs working in the pair of wavelength CHs. The ONUs transmit data in the pair of wavelength CHs in a time division multiplexing manner. The uplink and downlink wavelength CHs processed by different TWDM CTs are different. Each ONU may send uplink data in a specific uplink timeslot according to an instruction of the corresponding OLT CT.
For implementing load balancing, energy saving, ONU library type reduction and the like, ONUs in a TWDM PON system are colorless, that is, T-Txs and T-Rxs of all the ONUs have the same physical structures, and the T-Txs and T-Rxs of the ONUs are set to be tunable. The ONUs may tune working wavelengths of the T-Txs and the T-Rxs, thereby being able to work in uplink and downlink wavelength CHs of any OLT CT.
However, an ONU has different power consumption when working in different OLT CTs, and enabling the ONU to work in any OLT CT may not effectively reduce the power consumption of the ONU.